A high-speed digital-to-analog converter is needed for the high-speed generation of waveforms as necessary. The digital-to-analog converters with the fastest conversion rate made by an available art are difficult to obtain because they are not on the general market and they are very expensive when compared to commercial products. Therefore, digital-to-analog conversion devices are inter-leaved in order to avoid such problems (for instance, refer to U.S. Pat. No. 6,356,224). This inter-leaving has an advantage in that a commercial digital-to-analog converter that has a relatively low conversion rate and is inexpensive can be used. Conventional converters are also set forth in the following: JP Unexamined Patent Application (Kokai) 5-276,036, JP Unexamined Patent Application (Kokai) 11-195,988, JP Unexamined Patent Application (Kokai) 2002-217,732, and JP Unexamined Patent Application (Kokai) 2002-246,910.
On the other hand, the following problems can occur with inter-leaving. For instance, there are cases wherein, although it is small, there is a difference in performance between inter-leaved digital-to-analog converters. Moreover, even though inter-leaved digital-to-analog converters momentarily have exactly the same properties, it is difficult to always maintain this state. Furthermore, there are cases wherein the output signals of digital-to-analog converters cannot be switched at uniform intervals. That is, by means of conventional inter-leaving, signal precision is sacrificed for high-speed conversion. Therefore, an object of the present invention is to provide technology for generating signals with less distortion than in the past.